THURSDAY, Aug. 4, 2016 (HealthDay News) -- Acupuncture may benefit people who have memory loss, but don't yet have dementia, suggests a review by Chinese researchers of five earlier studies.

Nothing has yet been proven to halt the progression to dementia in those who are destined to progress. But, acupuncture used alone or along with another treatment, such as the medication nimodipine, might help retain some memory function, the researchers said.

But several doctors not involved with the review said it was too soon to say that acupuncture might be effective against dementia.

For the study, Min Deng and Xu-Feng Wang, from Wuhan University in China, reviewed five previously published studies done in 2012 and 2013.

The trials included nearly 600 people with mild cognitive impairment, a type of memory loss that's considered pre-dementia. About 5 percent to 10 percent of people with mild cognitive impairment develop dementia each year, the study authors noted.

The researchers concentrated on people who had a specific form of mild cognitive impairment called amnestic. People with this type of impairment are even more likely to develop dementia, the review authors said.

The studies compared the benefit of acupuncture alone versus nimodipine. Or, looked at the two treatments together compared to nimodipine alone.

Patients received treatment three to five times a week for eight weeks in four trials. The fifth trial lasted for three months.

The combined data from all five trials showed that those receiving acupuncture did better than those on nimodipine alone.

The acupuncture patients scored better on two tests of memory and dementia: the mini-mental state exam (a 30-point questionnaire that measures mental impairment), and picture recognition.

In addition, the combination of acupuncture and nimodipine improved scores on the mini-mental state exam compared with nimodipine alone, the researchers found.

Three trials reported side effects, which for acupuncture included fainting during treatment and slow bleeding at the needle sites. Side effects reported for nimodipine included nausea, constipation and mild headache, according to the report.

Dr. Remy Coeytaux is an associate professor in community and family medicine and an acupuncture researcher at Duke University in Durham, N.C. He was one of the experts reluctant to embrace the review's findings.

"The studies suggest that acupuncture is effective, but my degree of confidence in this finding is low, [but] it's not zero," Coeytaux said.

The problem is that "the quality of the studies really was poor, so that puts a damper on the findings, because it's hard to trust the data from the original studies," explained Coeytaux.

"There is high risk of bias in all the studies," he added.

Coeytaux suggested that some of the benefit seen from acupuncture might be a placebo effect. But, it's impossible from this review to know how much, if any, was a placebo effect, he explained.

What is known is encouraging, but there is need for a larger, better designed trial to really see if acupuncture can help, he said.

However, because there aren't any really effective treatments for memory loss, trying acupuncture is something patients can do -- it may not help, but it won't hurt, Coeytaux noted.

Another review skeptic is Dr. Sam Gandy, director of the Center for Cognitive Health at Mount Sinai Hospital in New York City. "I tend to believe some holistic interventions when properly executed," he said.

For example, Gandy noted that meditation in Alzheimer's disease patients is potentially credible and promising.

"That said, I don't believe anything until it is independently replicated," he said.

"I can imagine some ways in which acupuncture might increase alertness and attention and thereby memory, but I would want to see independent replication," Gandy added.

The new report was published Aug. 4 in the journal Acupuncture in Medicine.